The embodiments described herein relate generally to methods and apparatus for a dark field illumination system. More specifically, the embodiments described herein relate to methods and apparatus for an optical system outputting direct light and having a sensor.
Pen strokes by handheld devices such as electronic pens or styluses on display surfaces can be digitally recorded by optical tracking systems contained within the handheld devices. The optical tracking systems typically include miniaturized cameras or sensors that can digitally recorded the pen strokes on the display surfaces. Known optical tracking systems use opaque dots to register position with a digital pen. These dots are typically invisible to the naked eye but detectable by the optical tracking system. Such known optical tracking systems typically use a wide field of view to receive sufficient reflections from the dots and have relatively low resolution.
Accordingly, a need exists for an improved methods and apparatus for the accurate and high resolution determination of position information of handheld devices on display surfaces.